The present invention relates to an improvement in a method and apparatus for adjusting the operation time of a servosystem and, more particularly, to a device which is capable of readily adjusting the rotation speed of a servomoter.
Where a servomotor is used to drive a carriage of a printer or like load, its rotation speed is susceptive to various inaccuracy factors which may be typified by the friction torque of a mechanism associated with the load, torque constant of the servomotor, constants in a printed circuit board (PCB) and offset of an operational amplifier. Any fluctuation in the rotation speed of the servomotor would lead to various troubles such as an inaccurate printing speed of a printer and inaccurate stop characteristics of the servomotor.
A prior art expedient for the adjustment of the velocity of a servomotor has employed a variable resistor (volume) or a set of switches which are selectively opened and closed. The apparatus relying on a variable resistor, however, suffers from the drawback that one has to operate the variable resistor while constantly measuring the motor speed. Another drawback is that one cannot quickly re-adjust the motor speed unless manipulating the variable resistor at each time of maintenance. Meanwhile, the apparatus using a set of switches has to be furnished with a number of resistors and switches in one to one correspondence with minutely divided adjustment steps, which will be essential in this case for stabilizing the printing speed of a printer or the stop characteristics of a servomotor. This results in a bulky design of the apparatus due to the substantial area occupied by such elements on a printed circuit board, while increasing the cost to a disproportionate degree.